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What Are the Key Features of Chordates?
Which Clades Make Up the Chordates?
What Are the Major Groups of Vertebrates?
All chordates have four distinctive structures List them
notochord, nerve cord, Pharyngeal gill slits and post-anal tail
A _____: a stiff flexible rod extending the length of the body
A dorsal, hollow ____ ____: lies above the digestive tract and expands anteriorly to form the brain
___ ___ ___: located in the pharynx that may form respiratory organs or may appear as grooves
Pharyngeal gill slits
A ___ ___ ____ the chordate tail extends past the anus
In humans, the chordate features are best seen during embryonic development, but later...
we lose our notochord, gill slits, and tails
Only the ___ ___ ___ is retained in post embryonic human development
dorsal nerve cord
The chordates include three clades
Lancelets are marine filter-feeders they are usually,
small, fishlike, invertebrate chordates that retain all chordate features as adults
_____ include all chordates that have a skull enclosing a brain
Craniates group includes the hagfish and the ____— animals in which the embryonic notochord is replaced during development by a backbone, or ____ ____, composed of bone or _____ (which resembles bone, but is more flexible)
vertebrates, vertebral column, cartilage
Several adaptations have allowed vertebrates to successfully invade most habitats:
–presence of an internal skeleton that can grow and repair itself allowed for greater size and mobility
–Jaws evolved to allow these animals to exploit a much wider range of food sources than jawless animals that preceded them
–development of paired appendages (fins, legs, wings) helped to stabilize movement
–increased size and complexity of the brain and sensory structures allowed these animals to perceive their environment in detail and to respond in a variety of ways
Today, vertebrates include the following groups:
spinal cord is protected by cartilaginous segments, live in both fresh and salt waters –Marine forms must return to fresh water to spawn
This describes ...
Describe Cartilaginous Fishes
–include sharks, skates, and rays
–most are marine
–possess jaws and a cartilaginous skeleton
–body is protected by a leathery skin embedded with tiny scales
–Some filter feeders, most are predators
–Pump water through their gills
–Internal fertilization (unlike most other fish)
–2 chambered heart
–tend to sink when they stop swimming because they lack a swim bladder
Decribe Ray-finned fishes
–the angler fish, the moray eel, and the sea horse
–most diverse of the vertebrates
–Bony skeleton; scales over skin
–2 chambered heart; gills
–Important food source
–Populations of almost all economically important ray-finned fish species have declined drastically due to increased efficiency in their capture by humans
–Large predatory fish such as the tuna have been reduced to 10% of their original population sizes due to overfishing